javadoc build issue

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1909752 13f79535-47bb-0310-9956-ffa450edef68

build.gradle

         options.deprecation = true
         options.incremental = true
     }
+    tasks.withType(Test) {
+        systemProperty "file.encoding", "UTF-8"
+    }
+    tasks.withType(Javadoc) {
+        options.encoding = 'UTF-8'
+    }
 
     repositories {
         mavenCentral()